The present invention relates to plasma processing systems and methods and more particularly, to a plasma processing system and method which can suppress influences caused by a disturbance.
As a plasma processing system, there is known, for example, a system wherein an etching gas is introduced into a vacuum processing chamber so that plasma is generated under a vacuum pressure, and radicals or ions generated in the plasma react with a surface of a wafer to be processed for etching. In the dry etching system for performing such processing, the etching is carried out under manufacturing conditions (gas flow rate, gas pressure, input power, etching time, etc.) called recipe. The recipe is always kept constant in a specific manufacturing step (in the same process) of a semiconductor device. In this connection, the single process may sometimes be divided into several steps and the manufacturing conditions may be changed for each of the steps.
When a process using a dry etching system is executed in a semiconductor manufacturing step, wafer processing is carried out with manufacturing conditions called the recipe set constant for each wafer processing.
In a recent dry etching process which demands finer processing, however, a product generated by a reaction between a wafer and an etching gas is deposited on an inner wall of a processing chamber, an unnecessary gas called outgas is produced from the deposit, which results in a change with time in an environment within the processing chamber. Further, the environment within the chamber is also changed even by the temperature change of parts associated with the chamber and by the wear of the parts. Such a dry etching system is susceptible to various disturbance factors.
In addition, even variations in the shape dimensions of a mask formed in a lithography step as a pretreatment of the above etching processing have also a great effect on its etched result.
That is, even when etching processing is carried out with a constant recipe, it is difficult to obtain a constant performance due to various disturbances.
In view of the problems in the prior art, it is therefore an object of the present invention to provide a plasma processing control system and method which can suppress influences caused, in particular, by disturbances.
In order to solve the above problems, in accordance with an aspect of the present invention, there is provided a plasma processing control system which includes a plasma processor for performing plasma processing operation over a sample accommodated within a vacuum processing chamber, a sensor for monitoring process parameters during processing operation of the processor, means for providing a processed-result estimation model to estimate a processed result on the basis of a monitored output from the sensor and a preset processed-result prediction equation, means for providing an optimum recipe calculation model to calculate optimum processing conditions in such a manner that the processed result becomes a target value on the basis of the estimated result of the processed-result estimation model, and a controller for controlling the plasma processing system on the basis of the recipe generated using the optimum recipe calculation model.
In accordance with another aspect of the present invention, there is provided a method for performing plasma processing operation over a sample accommodated within a vacuum processing chamber, which includes the steps of monitoring process parameters during the processing operation, estimating a processed result on the basis of the monitored result, calculating correction values of processing conditions in such a manner that the processed result becomes a target value on the basis of an estimated result of the processed result to thereby generate an optimum recipe, and controlling a plasma processor on the basis of the generated optimum recipe.
Other objects, features and advantages of the present invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.